This invention concerns an alignment and holding mechanism for a pin grid array (PGA), particularly such a mechanism that is adapted to use the pins of the PGA to cause self-alignment within the mechanism.
In the art of testing PGA's and in the art of autoinsertion of PGA's, a common problem is to insure that the PGA is properly aligned so that it can be inserted into its socket, whether that socket is for testing or for the eventual placement of the PGA in a circuit. As a result, it is typical in the art to perform an alignment process before attempting the insertion. This alignment process is typically separate from the pick up and holding of the PGA which involves the use of a vacuum cup. In one prior art process, the vacuum cup is used to place the PGA in a V-block, i.e. a piece of metal in the shape of a right angle that is accurately machined to align the pins of the PGA on two sides in a particular location and orientataion. Then vacuum is released, and the PGA is allowed to settle to the proper location and orientation. Then the vacuum is applied again, now with the PGA in a known orinetation and position. The PGA can then be moved around robotically via the vacuum cup once this initiallization is complete. In another method, a V-block is not used, but air cylinders immediatly prior to test set insertion are used to properly align the PGA before insertion. The air cylinders also have a typical V-shaped alignment. Once the PGA is aligned, the air cyliders are moved back out of the way to allow insertion into the test block. Both of these process are two-step operations, in the sense that they are independent of the pick up and holding of the PGA. Hence, they take time that would not otherwise be required if the PGA were properly aligned in the pick up process itself.